Fluid streams, such as air streams, often carry contaminant material. In many instances it is desired to filter some or all of the contaminant materials from the fluid streams. For example, particulate contaminants can be carried by air streams into internal combustion engines for motorized vehicles or for power generation equipment. It is preferred for such systems that selected contaminant material, such as particulate contaminants, be removed from (or have its level reduced in) the air stream.
A variety of fluid filter arrangements have been developed for contaminant reduction. In general, however, continued improvements are sought.